Steel 5155 QT 44-48 HRC vs 5155 QT 50-55 HRC
Steel · 5155 temper comparison
5155 QT 44-48 HRC and 5155 QT 50-55 HRC are two conditions of the same steel grade, 5155: QT 44-48 HRC versus QT 50-55 HRC. The chemistry is identical, so every difference below comes from the condition. 5155 QT 50-55 HRC is the stronger of the two: yield strength 1,700 MPa (247 ksi) against 1,420 MPa (206 ksi) for 5155 QT 44-48 HRC, about 20% more; tensile strength follows at 1,930 MPa (280 ksi) vs 1,600 MPa (232 ksi). In exchange, 5155 QT 44-48 HRC is the more ductile: elongation 10% versus 8% for 5155 QT 50-55 HRC, and 5155 QT 50-55 HRC is harder (520 HB vs 435 HB). 5155 QT 44-48 HRC runs hotter in service (250°C vs 180°C continuous). On the shop floor, 5155 QT 44-48 HRC machines more easily (30 vs 18 out of 100).
5155 QT 44-48 HRCChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
5155 QT 50-55 HRCChoose it when strength drives the design.
5155 QT 44-48 HRC vs 5155 QT 50-55 HRC: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
5155 QT 44-48 HRC5155 QT 50-55 HRC
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 205 GPa29.7 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Compressive Strength 1,450 MPa210 ksi · Shear Strength 960 MPa139 ksi
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,420°C2,588 °F · Liquidus Temperature 1,480°C2,696 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 45 W/m·K26 BTU/hr·ft·°F · Specific Heat Capacity 475 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.3 µm/m·K6.8 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7.8 % IACS · Electrical Resistivity 2.2×10⁻⁷ Ω·m8.66 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 V · Corrosion Resistance 12 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Formability (cold)
Same in both: Weldability 20 / 100 · Brazeability / Solderability 30 / 100 · Polishability 65 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 30 MJ/kg12,898 BTU/lb · Embodied Carbon (primary production) 2.3 kg CO₂/kg · Embodied Water 55 L/kg6.6 gal/lb · Typical Recycled Content 30%
Strength versus weight
Yield strength against density for every steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
5155 QT 44-48 HRC vs 5155 QT 50-55 HRC — frequently asked
Is 5155 QT 50-55 HRC stronger than 5155 QT 44-48 HRC?
Yes. 5155 QT 50-55 HRC has a typical yield strength of 1,700 MPa (247 ksi) against 1,420 MPa (206 ksi) for 5155 QT 44-48 HRC — about 20% more. Tensile strength is 1,930 MPa (280 ksi) vs 1,600 MPa (232 ksi).
Which condition does FabDigit quote by default, QT 44-48 HRC or QT 50-55 HRC?
QT 44-48 HRC is the default 5155 condition in the FabDigit quote flow. The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which is easier to machine, 5155 QT 44-48 HRC or 5155 QT 50-55 HRC?
5155 QT 44-48 HRC, by a small margin. Both rate poor for machinability — 30/100 against 18/100 for 5155 QT 50-55 HRC.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 5155 QT 44-48 HRC and 5155 QT 50-55 HRC side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.